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Bought my z3 from a used-car dealer in June 2012, wet floor at first heavy rain. Got to wonder what the dealer knew and wouldn't reveal. Got a new top, leaks were sealed, no more water. Then my ABS system started going bonkers, first with very short brake applications, then finally the ABS and BRAKE lights came on, and took the dysfunctional subsystem out of computer circuit.

Brought the car to my indy BMW garage. Got a call a few days later to look at the car before work is performed. He pulled up the driver's side carpet, asking me if I smelled anything, since there was black mold under the carpet from years of saturation. Much of the car's floor was wet. He then pointed out a connector whose printed circuit board was heavily corroded (see arrow in the photo), indicating this was the problem, and will be replaced.

Anyone familiar with this connector? What else is often damaged by water remaining on the floor below the carpet? My ignorance: I would have thought a convertible would be protected from this kind of vulnerability to water.

That could be the "yaw" sensor, a component of the DSC system. I say could be, because I've never had to service one before.

The yaw sensor compares the direction that the car is going, to where the steering wheel is pointed, sensing an insipient spin, and would employ the ABS to tap the individual wheel's brake, keeping the car on course.

That could be the "yaw" sensor, a component of the DSC system. I say could be, because I've never had to service one before.

The yaw sensor compares the direction that the car is going, to where the steering wheel is pointed, sensing an insipient spin, and would employ the ABS to tap the individual wheel's brake, keeping the car on course.

You were right on the button - it was the "yaw" sensor, which my mechanic refers to by BMW's nomenclature, the rotation speed sensor. The unit in the other photo in this thread is the side impact sensor, cruddy but in good condition. The attached photo is the current state of affairs. With the heat and A/C controls detached, I looked for the hot-air gate, which sticks when in the closed position because of bare adhesive, but didn't locate it.